| Summary: | 碩士 === 國立臺灣海洋大學 === 材料工程研究所 === 103 === In recent years, circulating fluidized bed (CFB) boiler is widely used , there is no formal reference for using the byproduct co-firing fly ash . This industrial byproduct is derived from a CFB boiler. The combustion process which has a low combustion temperature (850 ~ 900 oC) will add limestone as a sorbent. The physical and chemical properties of CFFA are different from pulverized coal fly ash (PCFA). PCFA can be directly used in making concrete, but not CFFA. This study is divided into three phases. The first stage investigates that use CFFA for mortar’s cementitious influences. Fixed water-cement ratio 0.45. Test variable is the CFFA substitution cement amount which according to weight ratio 0%、25%、50%、75%、100%. Test project is the compressive strength test, the initial setting time test, mix water test. The second stage the performance in adding CFFA to cement mortar is also investigated and the results compared with PCFA mortar’s performance. Test variable is the water-cement ratio (0.45 and 0.55) , CFFA substitution cement amount which according to weight ratio 0%、10%、20%、30% , CFFA substitution fine aggregate amount which according to weight ratio 0%、5%、10%, PCFA substitution cement amount which according to weight ratio 0%、10%、20%、30%. Test project is the flow test, length change test, water absorption test, compressive strength test, resistance to sulphate test. The first stage investigates that mixed use CFFA and PCFA for mortar performance influences. Test variable is the water-cement ratio (0.45 and 0.55) , CFFA substitution cement amount which according to weight ratio 0%、10% , CFFA substitution fine aggregate amount which according to weight ratio 0%、5% ,PCFA substitution cement amount which according to weight ratio 0%、10%. Test project is the flow test, length change test, water absorption test, compressive strength test, resistance to sulphate test.
Test results indicate. The first stage (1)CFFA replace the cement amount Increase, requires more water to maintain the same flow values (2)CFFA replace the cement amount Increase mortar compressive strength decreased, longer the initial setting time. The second stage (1)CFFA replace cement quantity 30%, 2% added plasticizer does not improve flow values (2)CFFA replace fine aggregate, help to reduce water absorption, enhances ability to resist sulfate attack and increases compressive strength; CFFA replace cementitious materials, Increase water absorption, enhances ability to resist sulfate attack and reduce compressive strength (3)The same binder substitute, CFFA mortar shrinkage less than PCFA mortar (4)The same binder substitute, CFFA mortar compressive strength higher than PCFA mortar (5) The same binder substitute, mortar wet and dry cycle test compressive strength reduction percentage, CFFA mortar below the PCFA mortar. The third stage (1)Mixes CFFA and PCFA mortar shrinkage is less than using individual CFFA and PCFA mortar under the same quantity replacement (2)Mixes CFFA and PCFA mortar compressive strength is higher than using individual CFFA and PCFA mortar under the same quantity replacement (3)CFFA mortar wet and dry cycle test compressive strength reduction percentage is lower than using mixes CFFA and PCFA mortar under the same quantity replacement.
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